This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present disclosure. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
Dynamic sealing between two moving surfaces is applicable to many applications, including the travel of a cylindrical body through a tubular element. In the oil and gas industry, examples include a plunger in a well production tubing member, a pig through a production line, and Inflow Control Devices (ICDs). In such systems, as limited contact may be desirable in order to minimize the friction drag or to avoid the risk of the device being stuck, a flow region is present in the annulus between the two concentric cylinders that are in relative motion. In some cases, there may be a desire to control the pressure drop along the annulus as a means to control, for example, the flow of fluid from the region above the device and the region below it. In other cases, there may be the desire to minimize such flow in order to achieve a practical separation between the two regions.
One solution is disclosed in U.S. Pat. No. 6,200,103 (the '103 reference), which consists of cutting circular slots in the outer surface of the tool. The '103 reference suggests that the opening of such cavities would force the flow to generate some sort of toroidal vortices that are associated with additional friction and that, consequently, will increase the resistance to the flow in the gap between the plunger and the walls. Such cavities are commonly referred to as “turbulent sealers.” Although the idea was useful, the behavior of the flow inside the cavities as it is indicated in the '103 reference may not be correct (the direction of the streamlines is more complex than what is shown and depends on various parameters), thus indicating some lack of understanding of this type of fluid flow.
What is needed are methods and systems for generating an effective dynamic seal in a tool taking advantage of the fluid flow around the tool.
Other relevant material may be found in: Cooper R. K. and Raghunathan S. R., “Computation of Incompressible Flow Over Three-Dimensional Cavities,” Third International Conference on Advances in Fluid Mechanics (AFM'2000); Yao, H, Cooper, R. K., and Raghunathan, S. R., Incompressible laminar flow over a three-dimensional rectangular cavity, Journal of Thermal Science, Volume 9, Number 3, 2007; Miles, J. W. and Lee, Y. K., “Helmholtz Reonance of Harbors,” Journal of Fluid Mechanics, 67, pp. 445-467, (1959); O'Brien V., “Closed Streamlines Associated with Channel Flow Over a Cavity,” Physics of Fluids, 15, No. 12, (1972).